The present invention relates to the spatial localisation of sounds in a three dimensional space in the presence of movement of the sound source utilised to localise those sounds.
It is known to localise sounds at a particular location in the presence of movement of sources. For example, U.S. application Ser. No. 08/723,614 entitled xe2x80x9cMethods and Apparatus for Processing Spatialised Audioxe2x80x9d describes a system for the localisation of a particular sound to a three dimensional location around a listener in the presence of movement of headphone speakers or the like.
Unfortunately, the necessary complexity of the systems described in the aforementioned application results in hem being unduly expensive. There is therefore a general need for an alternative form of sound localisation which maintains substantially all the benefits of the aforementioned system but is also substantially simplified.
It is an object of the present invention to provide for a simplified system which allows for the appearance of localisation of sounds through utilisation of the human auditory system.
In accordance with the first aspect of the present invention there is provided a method of determining an audio output of a substantially spatially localised audio signal, said method comprising accurately stabilising the apparent spatial location of said audio signal for small movements of at least one real sound source and relatively less accurately stabilising said apparent location for large movements of said sound sources.
In accordance with a further aspect of the present invention there is provided a method of stabilising the apparent location of an audio signal having spatial components, in the presence of movement of emission sources designed to emit the audio signal whilst maintaining said apparent location, said method comprising the steps of:
(a) high pass filtering a signal proportional to the angular position of said emission sources;
(b) utilising said high pass filtered signal as an apparent angular position of said emission sources to determine an apparent location of said audio signal.
Preferably, the high pass filtering includes limiting said high pass filter signal, preferably utilising a nonlinear asymptotically bounded function.